The proposed research presents an experimental undertaking aimed at psychophysical investigation of temporal processing of speech and non-speech sounds in both normal and brain damaged listeners. The first part of the project consists of a series of psychoacoustic experiments in which experienced normal subjects will have to discriminate brief time intervals bounded by pairs of (synthetic) speech- or non-speech sounds, or to identify (categorize) speech sounds differing in one, temporally-based phonetic feature. In most of these experiments, a specific cueing sound may be present; its role will be to influence the subject's listening mode. The second part of the project is directed toward the question of left-right asymmetries in the perception of speech and non-speech sounds. It will also represent a set of psychoacoustic experiments in which normal subjects will be tested for ear differences in time discrimination with and without cues. The third part of the study contains experiments in which the subjects are left- and right-temporal-lobe damaged patients. Some experiments will investigate the patients' ability to distinguish speech and non-speech sounds that will differ in some temporal attribute. In other experiments the same patients will be tested for the efficiency of their right and left ear to process spectral information.